Epoxy compositions and their curing techniques are well-known and the patents issued on curable epoxy compositions number in the hundreds. Known curing agents include, among many others, polycarboxylic acids and anhydrides, amines, polyamides, imidazoles, and the like. Representative curing agents are described in U.S. Pat. No. 3,336,241. These curing agents may be employed with one or more catalysts or accelerators such as the stannous salts of monocarboxylic acids.
It will be appreciated that each and every one of the known epoxy-curing systems exhibits advantages over other systems, and, as importantly, disadvantages over the same systems. There is, of course, a continuing need to develop better epoxy curing compositions.
An epoxy curing system has how been found which is not only simple and produces rapid curing, but the resulting cured epoxy compositions exhibit excellent physical properties.
Accordingly, the present invention provides a curable epoxy composition comprising (1) an epoxy resin and (2) a curing amount of at least one "hard cation" catalyst.